In the article, it gives a description of the metaphysical properties associated with each shape and the corresponding chakra that it supports.

The Cube is earth and root - it grounds you and balances you so you can feel connected to earth and nature.

The Tetrahedron is fire and solar plexus - it helps to connect the physical and the spiritual and supports personal power.

The Octahedron is air and is connected to the heart - it helps us connect us to the deeper heart essence and helps us cultivate forgiveness and compassion for ourselves and others.

The dodecahedron is ether and is connected to the third eye, crown and the chakras above the crown. This helps us connect to the higher self and helps us cultivate a higher vibration, especially in meditation.

The icosahedron is connected to water and the sacral chakra. This energy helps us go with the flow of life with ease and unblocks and removes stressors that keep us "stuck".

So, if you use these crystalline shapes in meditation, they can facilitate healing on the chakra level or on a physical, emotional level. You can also place them on the chakras and have the intention of healing and see what happens! I'm including another article about healing the chakras which may give you more ideas on how to use these sets.